waves Flashcards

(53 cards)

1
Q

transverse waves vibrate ……. to the direction of energy transfer

A

transverse waves vibrate perpendicular to the direction of energy transfer

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2
Q

longitudinal waves vibrate ……. to the direction of energy transfer

A

longitudinal waves vibrate ** parallel ** to the direction of energy transfer

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3
Q

what are the highest and lowest points of transverse waves?

A

highest - peak
lowest - trough

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4
Q

what are the highest and lowest points of longituodinal waves?

A

highest - compression
lowest - rarefaction

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5
Q

what is amplitude?

A

max displacement of a vibrating particle

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6
Q

wave frequency equation

A

frequency = 1/ time period
(time period = time for one complete cycle of a wave)

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7
Q

wave speed equation

A

V= f x λ
(wave speed = frequency x wave length)

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8
Q

what is the human auditory range?

A

20 - 20K Hz

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9
Q

what type of waves are sound and ultrasound waves?

A

longitudinal

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10
Q
A
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11
Q

what is ultrasound?

A

sound waves with a frequency higher frequency than 20k Hz

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12
Q

how can ultrasounds be used to see the internal structure of a object?

A
  • ultrasound waves are reflected by boundaries in an object due to change in mediums
  • if you know the wave speed and time it takes for the wave to be reflected you can calculate how far away the boundary is
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13
Q

what are seismic waves?

A

waves produced by an eathquake

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14
Q

what are the 2 types of waves produced when an earthquake happens?

A

surface waves - travel across the earth’s surface
body waves - travel through core of the earth

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15
Q

what are P waves and their properties?

A

primary waves
- longitudinal
- travel through solids and liquid (mantle, outer core and inner core)
- faster than s waves

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16
Q

what are S waves and their properties?

A

sheer waves
- transverse
- only travel through solids (mantle, can’t travel through outer core because it is liquid, so can’t reach inner core)
- slower

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17
Q

how have p and s waves helped work out the structure of the earth?

A
  • refraction of p waves through the earth shows that the earth has different densities at different depths (presence of boundaries)
  • s waves can’t travel through liquid so it not being able to travel through the outer core shows that it is liquid
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18
Q

angle of reflection = ?

A

angle of reflection = angle of incidence

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19
Q

how do smooth objects reflect light compared to irregular objects?

A

smooth - light reflected in all one direction (specular reflection)
irregular - scatters light in lots of directions (diffuse reflection)

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20
Q

when light travels from a denser medium to a less dense material what way does it refract?

A

away from the normal

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21
Q

what can happen to waves at the boundary between 2 materials? (4)

A
  1. reflection
  2. refraction
  3. absorption
  4. trasmission
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22
Q

when light travels from a less dense medium to a denser material what way does it refract?

A

towards the normal

23
Q

what do waves transfer?

A

energy
(also info)

24
Q

required practical

describe a practical to measure the speed of sound in air - variables?

A

IV: The distance between Person A and Person B.
DV: The time taken for the sound to reach Person B.
CV: The medium (air) through which the sound travels, the temperature and humidity of the environment (as they affect sound speed). The same method of creating the sound (e.g., striking the block).

25
describe a practical to measure the speed of sound in air - method (6 steps) ?
1. person A stands with the wooden block at one end of the open space. 2.Person B stands at a known distance away from Person A (e.g., 100 meters), measured with a trundle wheel, ensuring they have a clear line of sight. 3.Person A strikes the wooden block together to create a sharp sound. 4.Person B starts the stopwatch when they see the action (wooden blocks striking) and stops it when they hear the sound. 5.Repeat the process 3 times to get more accurate measurements of the time. 6. use s=d/t to find speed of sound
26
# required practical describe an experiment to find out how the angle of refraction changes based on the angle of incidence for a glass block - variables?
IV - angle of incidence DV - angle of refraction CV - width of slit in ray box, medium light is passed through
27
describe an experiment to find out how the angle of refraction changes based on the angle of incidence for a glass block - method (8)
1. place the glass block on a piece of paper and trace it. 2. draw a line from your drawn box (glass block) at 90' (the normal) 3. use a protractor to measure and draw an angle of incidence every 10' from your normal (10' - 60') 4. line up the slit of the ray box on each drawn angle of incidence and pass the light through the block at that angle (repeating for each angle) 5. draw the emergent ray, then remove the glass block from the paper and connect the incidet ray and emergent ray with a line drawn with a ruler. 6. using a protractor, measure the angle of refraction (angle opposite angle of incidence, inside box) 7. repeat 3 times to get more accurate results 8. calculate a mean and draw a table of results
28
what are convex lenses (+ diagram)?
<------> converging
29
what are concave lenses (+ diagram)?
>----------< diverging
30
what are real images?
- light rays come together to form the image - the image can be captured on a screen eg retina
31
what are virtual images?
- light rays do not come together to form an image - the image cannot be captured on a screen
32
through a concave lens, where the object is behind 2 x the focal point (2F) the object appears...
- smaller - upright - virtual
33
through a convex lens, where the object is behind 2 x the focal point (2F) the object appears...
- smaller - real - inverted
34
through a convex lens, where the object is at 2 x the focal point (2F) the object appears...
- real - inverted - same size
35
through a convex lens, where the object is infront of 2 x the focal point (2F) but behind the focal point the object appears...
- larger - inverted - real
36
how do you draw ray diagrams (convex) ?
- draw an axis - draw the lens i the centre - draw the equidistant focal points and 2Fs - draw the object as a upright arrow - connect the top of the object to the lens, the make that ray pass through the focal point on the other side - draw a line from the object through the origin - where both lines meet is where the object is if it is real
37
what is refraction?
the change of speed of light waves as it moves through different mediums (bending light)
38
what are electromagnetic waves?
- transverse - can travel through vacum - all travel at 3 x 10^8
39
for electromagnetic waves : as wavelength increases, frequency...
as wavelength increases, frequency decreases
40
electromagnetic spectrum (long-short wavelength/ low-high frequency)
radio (10^4 hz) microwave (10^8 hz) infrared (10^12 hz) visible light (10^15 hz) ultraviolet (10^16 hz) x-ray (10^18 hz) gamma ray 910^20 hz)
41
how are radio waves used for commuication?
- radiowaves are made by oscillations in electrical circuits - when a current flows it creates an electromagnetic field, and when the current changes the field also changes - the changing current produces a radio wave - this is how transmitters work - recievers are when radio waves are absorbed, creating an alterating current with the same frequency as the radio wave itself
42
uses of microwaves (2)
**satellitecommunication** (refracted by ionosphere, then pass through space) **cooking**, through vibrating the water molecules in a piece of food, which the heats all the food through conduction
43
what is ionization?
when some types of electromagnetic radiation interact with atoms/molecules, the energy of the radiation is absorbed by the atom and gives the electron enough energy to escape the electrostatic force holding the atom together, making it become an ION
44
45
uses of x-rays (3)
- imaging (pass throuhh less dense material eg flesh, absorbed by denser material eg bone) - killing cancerous cells - crystallography (work out arrangement of atoms in crystals)
46
risks and percautions of x-rays and gamma rays
- ionising radiation can damage cells causing them to mutate uncontrollably (cancer) - wear lead apron, leave room/go behind a wall as a radiologist, limit area exposed to x-ray, limit x-rays/year
47
uses of gamma rays (2)
- medical and industrial imaging (radioactive tracer emmits gamma rays, detected by gamma camera) - sterlizing medical equipment (kills all living cells but doesn't damage the equipment
48
49
how does light mix to make different colours? (4)
red + blue = magenta red + green = yellow blue + green = cyan green + red + blue = white
50
how is the colour of a object determined?
- when light hits a opaque object it can only be reflected or absorbed - different surfaces reflect and absorb different colours - colour you see is the only wavelength/combination of wavelengths reflected (rest are absorbed)
51
how do colours change under coloured light?
the object will either appear the colour of the light eg white shirt under blue light = blue or black eg red shirt under blue light = black (since black is abscence of light)
52
what is a perfect black body?
a body where all radiation incident upon it is absorbed or emmitted perfectly, none is reflected/refracted
53
as temp increase (more infrared radiation), what happens to the intensity and wavelength?
temp increases wavelength decreases intensity increases